Hitherto, as a rotor for a rotating electrical machine, it has been widely known to use a permanent magnet (hereinafter simply referred to as “magnet”). In this type of rotor, in order to reduce cogging torque when applied to a motor, it has been proposed to divide a ring-shaped magnet into segmented magnets each having a semi-cylindrical sectional shape (see, for example, Patent Literature 1).
The magnet of the rotor disclosed in Patent Literature 1 has a semi-cylindrical sectional shape, and the thickness of the magnet in cross section is set to be smaller at both end sides than at a center portion thereof. A core of the rotor is formed into a substantially polygonal prism. At respective corner portions of the polygonal prism, radial projections are formed and located at upper and lower ends of the core.
Note that, in the core of the rotor having the above-mentioned shape, each magnet is bonded between the projections with use of an adhesive.
In this case, applicable methods for bonding the magnet include a method involving pressing each magnet from a radially outer side toward the center of the core while holding the magnet onto the core and a method involving dropping the magnet from an axially upper side of the core so as to be bonded at a predetermined position. Those methods, however, need a large-scale jig for magnet bonding.
In magnet bonding, the magnet is positioned in a state in which one side surface of the magnet abuts on one side of the projection of the core. In this case, the magnet is positioned appropriately in a circumferential direction of the core, but there is no positioning means for an axis direction. Because of the relationship that an axial length of the core is larger than an axial length of the magnet, arrangement work is performed so as to prevent the magnet from protruding from the core.